Welcome Amelia J. I'm a horsey person too. I volunteer for an organisation called Triple R Equine Welfare here in Victoria.
www.triplerequinewelfare.org.au
I like your goals re: retraining horses that otherwise have no hope. I currently have a rescue here with me that I have been rehabilitating. It has been incredibly rewarding. She was abused and had no trust in humans. When I first met her, she would not allow anyone to touch her, and she would constantly turn her hind quarters at you just because she was so fearful and knew that was her best defence. Here is her story:
http://www.triplerequinewelfare.org.au/gladys.html
The statistics are alarming, aren't they. Even more alarming are the number of horses bred for racing that just get discarded and sent to slaughter when they don't make the grade. We're talking some 18,000 foals born every year, and only a tiny % make it to the track, and there most certainly are not enough homes for them once their racing "career" is over.
I am staggered at the number of people who don't know that horses end up in dog food tins. Have a look at the labels, most of them say, "meat including beef, lamb and pork" (or something like that) It likely also includes horse, but they would never say that.
Ooops, so sorry for hijacking your thread.